Switch roof trusses garage

[niclas47]

Hello! I have a garage with a storage/carport next to it. I'm going to tear down the partition wall to create a double garage. Can anyone help me with how these roof trusses should be transferred?

 

[AG A]

In my opinion, they don't seem to need switching, as long as you don't plan to use the upstairs.

 

[niclas47]

Okay, thanks 😊

 

[Magnus E K]

Isn't it framework trusses that require support from a heart wall beneath them? If that wall is removed, the trusses would need to be completely rebuilt into a truss system. You would need to leave a number of posts with a beam above them.

 

[AG A]

Isn't it truss rafters that require support from a load-bearing wall beneath them? If that wall is removed, the trusses would need to be completely rebuilt into a framework. You can leave a number of posts with a beam over them.

You are both right and wrong. But more generally, one can say that truss rafters, in normal lumber dimensions, do require support. At least if the span exceeds 6 meters. But that's because the actual point of a truss rafter is really to be able to use the attic space and thus load the floor significantly. But when there is no floor or floor joists, it becomes almost impossible to use the attic. Without a load on the attic, no support is needed underneath.

 

[niclas47]

Isn't it framework trusses that require support from a center wall underneath? If that wall is removed, the trusses would need to be completely rebuilt into truss form. You'd have to leave a number of posts with a beam over them.

Yes, that's what I initially thought too, placing a steel/glulam beam doesn't matter much in a garage but it would have been nice to avoid it.

 

[niclas47]

You are both right and wrong. But more generally, one can say that truss rafters, in normal timber dimensions, require support. At least if the span exceeds 6 meters. But that is because the whole point of a truss rafter is really to be able to use the attic and thereby load the floor substantially. But if there is no floor, or intermediate joists, it's almost impossible to use the attic. Without load in the attic, no support is needed underneath.

I now see that the rafters are spliced on the partition wall. What could be the dimension of glulam if you are to place it underneath for support? The wall is 11 meters but 5.5-6 meters of it will be removed.

 

[Lulaua]

You are both right and wrong. But more generally, you can say that trusses, in normal timber dimensions, require support. At least if the span exceeds 6 meters. But that's because the main point of a truss is really to be able to use the attic, and thus load the floor properly. But since there is no floor or intermediate joists, it becomes almost impossible to use the attic. Without load on the attic, no support is needed underneath.

Calm down now, the support beams transfer loads from the roof down to the underarm which is supported by the wall. If the support is to be removed, either the wall must be replaced with a beam or the trusses must be modified with a framework.

 

[Utsliten och utdömd]

I now see that the roof trusses are spliced on the center wall. What can be considered for the dimension of glulam if it is to be placed under as support? The wall is 11 meters but 5.5-6 meters of it should be removed.

You place the beam above the roof trusses and attach them in the displacement. Then you can embed proper posts in the gable walls and won't need to consider the ceiling height when sizing the glulam beam.

 

[AG A]

Calm down now, the support legs transfer loads from the roof down to the forearm which is supported by the wall. If the support is to be removed, either the wall must be replaced with a beam or the roof trusses must be rebuilt with a truss.

You are speaking with a structural engineer, and I am calm. As I've said, it's both right and wrong. For shorter spans, it's fine without support. Especially when the attic floor is not to be loaded.

 

[AG A]

I now see that the roof trusses are spliced on the heart wall. What dimensions can one consider for glulam if it is to be placed underneath for support? The wall is 11 meters but I want to remove 5.5-6 meters of it.

I saw that from the very beginning. BUT, they are spliced according to "the art's all rules," and therefore hold just as well as unspliced.